From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BE005C3A5A1 for ; Thu, 22 Aug 2019 11:28:44 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7B1D0233FD for ; Thu, 22 Aug 2019 11:28:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="cRqKwnFB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7B1D0233FD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 50D25E1B; Thu, 22 Aug 2019 11:28:44 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 09784D9D for ; Thu, 22 Aug 2019 11:28:44 +0000 (UTC) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 6447389B for ; Thu, 22 Aug 2019 11:28:43 +0000 (UTC) Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EC96F206DD; Thu, 22 Aug 2019 11:28:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1566473323; bh=aBkIxbh8H3Md/T5wqzLj1FFJMdZskQl8pfMvLAQCue8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cRqKwnFB3bV6vcqeK1ELh9lo1EZIXzFUSvjWaooDsaBrAF6sZVylgUg+B+9AUI0HK LZs/kPtu6YgpNmp0nV0mH/J+jRGEqw1Y0uypY9rP1OvK/xTDzVppBV4oBQ7FT0uZ+x hJWF8o5esN6BksMzW4J0W0RDz5436nqzasB9fZAA= Date: Thu, 22 Aug 2019 12:28:36 +0100 From: Will Deacon To: Robin Murphy Subject: Re: [PATCH v10 09/23] iommu/io-pgtable-arm-v7s: Extend to support PA[33:32] for MediaTek Message-ID: <20190822112836.efodtwu3souq3uwa@willie-the-truck> References: <1566395606-7975-1-git-send-email-yong.wu@mediatek.com> <1566395606-7975-10-git-send-email-yong.wu@mediatek.com> <20190821152448.qmoqjh5zznfpdi6n@willie-the-truck> <1566464186.11621.7.camel@mhfsdcap03> <10d5122d-3375-161b-9356-2ddfc1c835bd@arm.com> <20190822101749.3kwzd5lb7zinsord@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Cc: youlin.pei@mediatek.com, devicetree@vger.kernel.org, Nicolas Boichat , cui.zhang@mediatek.com, srv_heupstream@mediatek.com, Tomasz Figa , linux-kernel@vger.kernel.org, Evan Green , chao.hao@mediatek.com, iommu@lists.linux-foundation.org, Rob Herring , linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, Matthias Brugger , ming-fan.chen@mediatek.com, anan.sun@mediatek.com, Matthias Kaehlcke X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org On Thu, Aug 22, 2019 at 11:57:11AM +0100, Robin Murphy wrote: > On 2019-08-22 11:17 am, Will Deacon wrote: > > On Thu, Aug 22, 2019 at 11:08:58AM +0100, Robin Murphy wrote: > > > On 2019-08-22 9:56 am, Yong Wu wrote: > > > > On Wed, 2019-08-21 at 16:24 +0100, Will Deacon wrote: > > > > > On Wed, Aug 21, 2019 at 09:53:12PM +0800, Yong Wu wrote: > > > > > > MediaTek extend the arm v7s descriptor to support up to 34 bits PA where > > > > > > the bit32 and bit33 are encoded in the bit9 and bit4 of the PTE > > > > > > respectively. Meanwhile the iova still is 32bits. > > > > > > > > > > > > Regarding whether the pagetable address could be over 4GB, the mt8183 > > > > > > support it while the previous mt8173 don't, thus keep it as is. > > > > > > > > > > > > Signed-off-by: Yong Wu > > > > > > --- > > > > > > drivers/iommu/io-pgtable-arm-v7s.c | 32 +++++++++++++++++++++++++------- > > > > > > include/linux/io-pgtable.h | 7 +++---- > > > > > > 2 files changed, 28 insertions(+), 11 deletions(-) > > > > > > > > > > [...] > > > > > > > > > > > @@ -731,7 +747,9 @@ static struct io_pgtable *arm_v7s_alloc_pgtable(struct io_pgtable_cfg *cfg, > > > > > > { > > > > > > struct arm_v7s_io_pgtable *data; > > > > > > - if (cfg->ias > ARM_V7S_ADDR_BITS || cfg->oas > ARM_V7S_ADDR_BITS) > > > > > > + if (cfg->ias > ARM_V7S_ADDR_BITS || > > > > > > + (cfg->oas > ARM_V7S_ADDR_BITS && > > > > > > + !(cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_EXT))) > > > > > > > > > > Please can you instead change arm_v7s_alloc_pgtable() so that it allows an > > > > > ias of up to 34 when the IO_PGTABLE_QUIRK_ARM_MTK_EXT is set? > > > > > > > > Here I only simply skip the oas checking for our case. then which way do > > > > your prefer? something like you commented before:? > > > > > > > > > > > > if (cfg->ias > ARM_V7S_ADDR_BITS) > > > > return NULL; > > > > > > > > if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_EXT) { > > > > if (!IS_ENABLED(CONFIG_PHYS_ADDR_T_64BIT)) > > > > cfg->oas = min(cfg->oas, ARM_V7S_ADDR_BITS); > > > > else if (cfg->oas > 34) > > > > return NULL; > > > > } else if (cfg->oas > ARM_V7S_ADDR_BITS) { > > > > return NULL; > > > > } > > > > > > All it should take is something like: > > > > > > if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_EXT) > > > max_oas = 34; > > > else > > > max_oas = 32; > > > if (cfg->oas > max_oas) > > > return NULL; > > > > > > or even just: > > > > > > if (cfg->oas > 32 || > > > (cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_EXT && cfg->oas > 34)) > > > return NULL; > > > > > > (and if we prefer the latter style, perhaps we could introduce some kind of > > > "is_mtk_4gb()" helper to save on verbosity) > > > > I wondered the same thing, but another place we'd want the check is in > > iopte_to_paddr() which probably needs the PHYS_ADDR_T check to avoid GCC > > warnings, although I didn't try it. > > I'm pretty sure I confirmed that "paddr |= BIT_ULL(32)" doesn't warn when > phys_addt_t is 32-bit - it's well-defined unsigned integer truncation after > all, and if GCC starts warning about all the valid no-op code it optimises > away then it's going to run up against IS_ENABLED() first and foremost ;) You're quite right, although we live in a world where GCC shouts at us about missing comments in switch statements so I think my worry was justified! > > So if we did: > > > > static bool cfg_mtk_ext_enabled(struct io_pgtable_cfg *cfg) > > { > > return IS_ENABLED(CONFIG_PHYS_ADDR_T_64BIT) && > > cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_EXT; > > } > > > > Then I suppose we could do this in _alloc(): > > > > if (cfg->oas > cfg_mtk_ext_enabled(cfg) ? 34 : ARM_V7S_ADDR_BITS) > > return NULL; ^^ Apparantly, I left the bracketting here as an exercise to the reader. > > > > and then this in iopte_to_paddr(): > > > > [...] > > > > paddr = pte & mask; > > if (!cfg_mtk_ext_enabled(cfg)) > > return paddr; > > > > if (pte & ARM_V7S_ATTR_MTK_PA_BIT32) > > paddr |= ... > > > > [...] > > > > What do you reckon? > > Yeah, that's the general shape of things I was picturing - I'm not that > fussed about the PHYS_ADDR_T_64BIT thing, especially if it's wrapped up in > just one place, so if you do want to keep it as belt-and-braces I'll just > consider it a slight code size optimisation for 32-bit builds. Ok, great. Yong Wu -- are you ok respinning with the above + missing brackets? Will _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu